1. Field of the Invention
The present invention relates generally to a brake system and, more particularly, to an auxiliary brake system which operates in conjunction with a vehicle's hydraulic brake system to allow a driver independently to control the wheels on the left or right side of the vehicle.
2. Description of the Related Art
In the related art, many auxiliary braking and brake related steering systems are known. Most of these address problems in conjunction with anti-skid, or anti-lock braking systems. These systems address the problems associated with traction control of a vehicle on pavement.
However, a different set of problems occurs from the use of a four-wheel-drive vehicle, especially in "off-road" or under slick conditions. Under such conditions, a driver of a four-wheel-drive vehicle may encounter a situation where the vehicle may become stranded due to the wheels on one side of the vehicle lose traction and begin to spin. This can occur when crossing a muddy or snow covered hill, for example. Under such situations, typical anti-lock braking systems are ineffective. In these situations, the ability to brake the wheels on only one side of the vehicle will greatly improve the maneuverability and control of a four-wheel-drive vehicle.
Numerous attempts have been made to improve braking systems and improve traction, stopping, and steering problems. For instance, U.S. Pat. No. 5,275,477 issued in the name of Schaefer et al., discloses a hydraulic dual-circuit brake system. However, a hydraulic dual-circuit brake system made in accordance with this reference merely distributes braking pressure between front axle and rear axle, and does not address the problems associated with the use of four-wheel-drive vehicles in off-road applications.
Also, in U.S. Pat. No. 5,234,264 issued in the name of Willmann et al., a brake system is disclosed which distributes braking pressure between all four wheels. Such an anti-skid device, however, would not assist the user of a four-wheel-drive vehicle in off-road applications, in that the spinning of the wheels during such activity would merely cause the braking pressure to be evenly distributed as in a regular, non-antiskid system.
Additionally, U.S. Pat. No. 5,171,071 issued in the name of Takata et al. discloses a brake system to improve brake pedal travel and response during anti-lock and traction control. Also, in U.S. Pat. No. 5,089,967 issued in the name of Haseda et al., an auxiliary steering system associated with anti-skid control system for use in motor vehicle is disclosed. In both of these reference the brake systems disclosed indicate improvements in the feedback dampening and distribution of braking pressure in anti-lock braking systems, but again do not address the problems associated with the use of four-wheel-drive vehicles in off-road applications.
Finally, in U.S. Pat. No. 5,241,479 issued in the name of Matusda et al., a switchable mode traction control method for vehicle is disclosed. However, the method disclosed in the Matusda et al. reference merely shifts braking force to the left or right drive wheel in a conventional two-wheel-drive vehicle if slippage is detected, and once again does not address the problems associated with the use of four-wheel-drive vehicles in off-road applications.
A need has therefore been felt for an improved but less complex mechanism that operates in conjunction with a vehicle's hydraulic brake system to allow a driver independently to control the wheels on the left or right side of a four-wheel-drive vehicle during periods where the vehicle becomes stranded in mud, snow, or other conditions where low-speed traction difficulties occur.